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400 exhaust manifold bolts...

Posted By: ramman16248

400 exhaust manifold bolts... - 08/16/18 01:08 AM

I am tearing down my 400. the manifold bolts in the center of the exhaust manifold have an odd looking bolt, where the head of the bolt is about the same diameter as the shank of it... what tool do you use to remove them?? there isn't a traditional 6 point or 12 point head on it. The motor is original and has never been worked on to this level, so the bolts are probably original to it. Thanks, Jay
Posted By: ross

Re: 400 exhaust manifold bolts... - 08/16/18 02:11 AM

Can you post a pic
Posted By: ramman16248

Re: 400 exhaust manifold bolts... - 08/16/18 02:21 AM

I will try to get one tomorrow....
Posted By: radar

Re: 400 exhaust manifold bolts... - 08/16/18 04:59 AM

I just took apart a 400 from 1978 I remember that some of the bolts or studs were real thick or had a special shape. I just looked through all my baggies of bolts in the garage and couldn’t find them but they unscrewed just fine despite their special shape- they were somewhat memorable but didn’t cause any difficulty.

Good luck hopefully somebody here has pics or a part #
Posted By: reknapp52

Re: 400 exhaust manifold bolts... - 08/16/18 05:35 AM

A little bit off topic, but-----I am also tearing down a 400 truck engine that has been sitting in the way in my garage for about 12 years. Are there any parts worth anything besides the block? It is a 1975 engine with 452 heads. Sorry, the exhaust manifolds were removed years ago.
Posted By: ZIPPY

Re: 400 exhaust manifold bolts... - 08/16/18 05:08 PM

Maybe this will help. The weird looking nuts at the bottom are usually used in a hole or three here and there depending on the exact model.

Attached picture hp manifold bolts.JPG
Posted By: B1MAXX

Re: 400 exhaust manifold bolts... - 08/16/18 05:12 PM

Those will be shanked nuts not bolts. The hex originally is the same diameter of the shank. These had a typical hex 6-point hex. What happens is they rust away and become all kinds of funny shapes. I usually beat a smaller socket over them and then take them of.
Posted By: radar

Re: 400 exhaust manifold bolts... - 08/16/18 05:34 PM

Yup! Those are exactly the ones I pulled off in the above pic!

Originally Posted By reknapp52
A little bit off topic, but-----I am also tearing down a 400 truck engine that has been sitting in the way in my garage for about 12 years. Are there any parts worth anything besides the block? It is a 1975 engine with 452 heads. Sorry, the exhaust manifolds were removed years ago.


Mine had the heads on it that are the same as the desireable earlier big block heads but with hardened seats. I forget the casting # but I pressure washed and wire brushed them and sold them on craigslist for $100 inside a couple weeks.

Cast crank = scrap, valvetrain=scrap (keep the rockers and pushrods), my water pump housing looks like a million bucks after a good cleaning and paint. Lots of good bolts and nuts to clean and wirebrush if you’re a cheapskate like me. My intake and valve covers haven’t sold at giveaway prices I will probably scrap them too but it never hurts to have a coffee can full of the little triangles. I cleaned up and painted the valley hold downs. Basically just the heads and any small parts ot unique hardware that are a pain in the neck and nickel and dime you to death when your budget is getting smaller at the end of a build.

Good luck
Posted By: ZIPPY

Re: 400 exhaust manifold bolts... - 08/16/18 07:43 PM

Yeah, they rust into various forms... Then the stud seizes inside em, and it looks just like a bolt from Jupiter....
Posted By: ramman16248

Re: 400 exhaust manifold bolts... - 08/18/18 04:34 AM

That's exactly what they are, did and that it exactly how I got them out!!!! LOL!!! Thanks!!!!!
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